Shoot Dry Matter Weight Research Articles

Genome-wide identification and analysis of the CNGC gene family in upland cotton under multiple stress conditions

BackgroundThe cyclic nucleotide-gated channel (CNGC) gene family plays a significant role in the uptake of both essential and toxic cations, and has a role in enhancing tolerance to various forms of abiotic stresses as well as the modulation of the heavy metal toxicity to plant through the absorption of heavy metals.ResultsA complete genome-wide identification and functional characterization of the cotton CNGC genes was carried out, in which 55, 28, and 29 CNGC genes were identified in Gossypium hirsutum, G. raimondii, and G. arboreum, respectively. The protein encoded by the CNGC genes exhibited GRAVY value below zero, indicating their hydrophilic property. CNGC genes were unevenly distributed in 19 out of 26 chromosomes, in which the highest density were observed on Ah05, with 8 genes. High gene coverage was observed among the diploid cotton species, with CNGC genes mapped on all A chromosomes and on 11 out of 13 of D chromosomes. The majority of CNGC proteins were localized in the endoplasmic reticulum, nucleus, and plasma membrane. Gene expression analysis revealed the up-regulation of Gh_A01G0520 (CNGC4) and Gh_D13G1974 (CNGC5) across various forms of abiotic stresses. Moreover, down-regulation of Gh_A01G0520 (CNGC4) and Gh_D13G1974 (CNGC5) in CNGCs silenced plants caused the significantly reduced ability to tolerate drought and salt stresses. All CNGCs silenced plants were recorded to have significantly low content of antioxidants but relatively higher content of oxidant, including MDA and H2O2. Furthermore, SPAD, CMS (cell membrane stability), ELWL (excised leaf water loss), SDW (shoot dry matter weight), and RDW (root dry matter weight) were all lower in CNGCs silenced plants compared with the wild type plants.ConclusionSignificant reduction in antioxidant content and negative effects of physiological and morphological characters in CNGCs silenced plants has revealed the novel role of CNGC genes in enhancing cell integrity under abiotic stress conditions. These results provide vital information that will expand our understanding of the CNGC gene family in cotton and other plants, thus promoting the integration of these genes in the development of the environmental resilient plants.

Genome-wide association analysis reveals genetic variations and candidate genes associated with salt tolerance related traits in Gossypium hirsutum

BackgroundCotton is more resistant to salt and drought stresses as compared to other field crops, which makes itself as a pioneer industrial crop in saline-alkali lands. However, abiotic stresses still negatively affect its growth and development significantly. It is therefore important to breed salt tolerance varieties which can help accelerate the improvement of cotton production. The development of molecular markers linked to causal genes has provided an effective and efficient approach for improving salt tolerance.ResultsIn this study, a genome-wide association study (GWAS) of salt tolerance related traits at seedling stage was performed based on 2 years of phenotype identification for 217 representative upland cotton cultivars by genotyping-by-sequencing (GBS) platform. A total of 51,060 single nucleotide polymorphisms (SNPs) unevenly distributed among 26 chromosomes were screened across the cotton cultivars, and 25 associations with 27 SNPs scattered over 12 chromosomes were detected significantly (−log10p > 4) associated with three salt tolerance related traits in 2016 and 2017. Among these, the associations on chromosome A13 and D08 for relative plant height (RPH), A07 for relative shoot fresh matter weight (RSFW), A08 and A13 for relative shoot dry matter weight (RSDW) were expressed in both environments, indicating that they were likely to be stable quantitative trait loci (QTLs). A total of 12 salt-induced candidate genes were identified differentially expressed by the combination of GWAS and transcriptome analysis. Three promising genes were selected for preliminary function verification of salt tolerance. The increase of GH_A13G0171-silenced plants in salt related traits under salt stress indicated its negative function in regulating the salt stress response.ConclusionsThese results provided important genetic variations and candidate genes for accelerating the improvement of salt tolerance in cotton.

Seedling production of Coffea arabica from different cultivars in a modified hydroponic system and nursery using different containers

ABSTRACT The development of modified hydroponic cultivation has aroused interest and its use has enabled advantages in several crops, but studies for coffee are still scarce. Thus, the objective of this research was to evaluate seedling production of three Coffea arabica cultivars (Mundo Novo IAC-376-4, Catuaí IAC-62 Amarelo and MGS Paraíso 2), in a modified hydroponic system, and to compare it with the nursery production system, using plastic polyethylene tubettes and bags. Coffee seedlings in the development phase with cotyledon leaves, were cultivated in both cultivation systems. At 90 days after the implementation of the experiment, the seedlings were analyzed for growth (height, stem diameter, total number, leaf area, root area, root and shoot dry matter weight), and physiological characteristics (chlorophyll content and stomatal conductance). For the statistical analysis, a completely randomized design (CRD) was used in a factorial scheme 3 (cultivars) x 2 (containers) x 2 (cultivation systems), with four replications of ten plants per plot. The innovative production system of coffee seedlings in modified hydroponics, in combination with the use of polyethylene bags, provided greater growth of coffee seedlings with better physiological characteristics. Among the cultivars tested, MGS Paraíso 2 stood out with higher seedling growth (number of leaves, stem diameter and root and shoot dry matter weight).

The root transcriptome analyses of peanut wild species Arachis correntina (Burkart) Krapov. & W.C. Gregory and cultivated variety Xiaobaisha in response to benzoic acid and p-cumaric acid stress

Allelopathy is the main cause of continuous cropping obstacles. Peanut wild species Arachis correntina (Burkart) Krapov. & W.C. Gregory is more resistant to continuous cropping obstacle than cultivated peanut, but its molecular mechanism in response to allelochemicals remains unknown. Benzoic acid (BA) and p-cumaric acid (PCA) are known allelochemical. To gain more insight into cellular response to BA and PCA, we applied high-throughput genetic sequencing to study the transcriptome changes of peanut cultivated variety Xiaobaisha and wild species A. correntina in the presence of 2 mM BA and PCA. The result showed that A. correntina resistance to BA and PCA stress was more weaker than Xiaobaisha. BA and PCA decreased significant shoot length and dry matter weight of A. correntina. Differentially expressed genes (DGEs) related to flavonoid biosynthesis, phenylpropanoid biosynthesis, plant–pathogen interaction and plant hormone signal transduction were transcribed less in A. correntina than Xiaobaisha under BA and PCA stress, including the less up-regulated genes involving in phenylpropane and flavonoid biosynthesis, detoxifying enzymes, Auxin responsive protein, WRKY family and Ef-hand, which might contribute to A. correntina’s weak resistance to BA and PCA stress. The results showed that the resistance to single allelopathic substance might not be the reason for A. correntina resistance to continuous cropping obstacle. In addition, DGEs of both A. correntina and Xiaobaisha were significantly enriched in the pathways associated with isoflavonoid biosynthesis and glutathione metabolism under BA and PCA stress. This was the first report on identification of DGEs under BA and PCA stress between peanut cultivated variety and wild species. The result would be great helpful to insight into the mechanisms of peanut response to allelochemicals stress.

Evaluation of fertigation technique for phosphorus application of maize in the semi-arid region of Northeast China

To determine the best phosphorus (P) fertilizer management strategy in chernozem soil in the semi-arid region of Northeast China, a field experiment under film mulched drip irrigation was conducted for two consecutive years. Five P application methods were tested, including no P fertilizer applied (P0); P fertilizer one-time basal application (P1); one fertigation one time (P2); fertigation twice (P3) and fertigation four times (P4). The shoot dry matter weight, phosphorus accumulation, yield and POlsen in soil were measured regularly during the maize growing season. The results demonstrated that P fertilizer application methods imposed significant effects on dry shoot matter, the apparent P loss, P fertilizer use efficiency and yield of maize (P < 0.05). The yield, P agrinomic efficiency and P recovery efficiency of P4 treatment were significantly higher than P1 treatment by 4.2, 39.7, and 66.4% across two year. In addition, P4 treatment significantly enhanced the shoot dry matter weight after V12 stage, post-silking P uptake and reduced the apparent P loss. In conclusion, P fertigation and a rational frequency (e.g., fertigation four times) enable to keep the maximum grain yield, the shoot dry matter, and recovery efficiency of P fertilizer (66.4%) though changing agronomic methods for efficient acquisition of P toward a sustainable and productive agricultural fertigation system.

Effect of a novel hydrogel amendment and seedling plugs volume on the quality of ornamental/miniature tomato

The market for ornamental/miniature plants values aesthetic morphological characteristics, which give harmony to the potted plant. These traits depend on the growing media capacity to maintain quality and plant longevity. The use of hydrogels has increased recently in order to achieve visually attractive and long-lasting plants. Thus, this study aimed to evaluate the effects of a novel hydrogel (H) amendment and seedling plugs volume (SPV) on the quality of ornamental/miniature tomato. Seedlings of tomato cv. BRS Finestra were produced in 200 and 162 plugs plastic trays - with 18 cm³ trapezium-shaped plugs and 50 cm³ conically shaped plugs, respectively. 18 cm³ plugs and H amendment presented several significant responses for plant characters - height, soluble solids, number of leaves, stem diameter, shoot dry matter and fruits weight per plant; making evident the advantages of using a growing medium of smaller volume and this copolymer amendement. Although consistent results were obtained, a combination of both these factors in terms of an optimal aesthetic value and considering all the morphological traits could not be accomplished. Therefore it’s necessary to study other elements such as plant nutrition and the use of plant growth regulators to complement them, aiming to promote better quality.

Influence of selenium on root morphology and photosynthetic characteristics of winter wheat under cadmium stress

To explore the feasibility of reducing cadmium (Cd) concentrations and alleviating Cd toxicity via selenium (Se), this study investigated the effects of Se on the root morphology, photosynthetic parameters, and Se, and Cd concentrations in winter wheat under different Cd stress levels. Three Cd levels (0, 5 and 10 μM) and three Se levels (0, 1 and 5 μM) were applied in a hydroponics test. The results showed that increases in Cd stress significantly decreased the shoot and root dry matter weight, root length, root volume, root effective surface area, root total surface area, Se concentration, Se accumulation, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr) and intercellular CO2 concentration (Ci). Increases in Cd stress significantly increased the Cd concentration and accumulation in shoots and roots, the root average diameter, and the stomatal limiting value (Ls). There were significant relationships between the root Cd concentrations and the root morphology parameters, shoot Cd concentrations and photosynthetic characteristics of winter wheat. The Se1 and Se5 treatments effectively increased the shoot dry matter weight, root length, root volume, root effective surface area and root total surface area and decreased the shoot Cd concentration, when Cd stress was at the medium level (Cd5). Only the Se1 treatment effectively increased the Gs, Tr and Ci under the Cd5 treatment. When Cd stress was at the high level (Cd10), the Se5 treatment had greater effects on root growth than the Se1 treatment, the Se levels had no pronounced effect on the shoot dry weight and Cd concentration in winter wheat. Meanwhile, the root Se concentration was closely related to each root morphology parameter. Cd stress inhibited the root growth and leaf photosynthesis of winter wheat, and a high enough Se supply reduced the Cd toxicity by enhancing the root growth of winter wheat.

Residual effect of organic fertilization on radish production

ABSTRACT this research aimed to evaluate the residual effect of doses of organic compost on the radish production, as well as its effect on soil chemical properties. experiments were conducted in two areas (“low” and “high” soil fertility). prior to this, these areas were first used to evaluate the influence of organic compost doses on endive production. after harvesting endive, radish seeds were sown into the same plots used for endive to evaluate the residual effect. the six treatments consisted of organic compost doses (0, 35, 70, 105, 140 and 175 t ha-1), evaluated in a complete block experimental design, with four replications. vegetative characteristics of radish plants (shoot, root and total fresh and dry matter weight, plant height and root diameter) and soil characteristics (macronutrient content, ph, h+al, organic matter, sum of bases, cation exchange capacity and base saturation) in two dates (11 days after the endive transplant and at the end of the radish cycle) were evaluated. no significant difference was observed for all doses of organic compost in the “low” soil fertility area, obtaining only non-commercial roots (average fresh weight of 5.01 g per root). in the “high” soil fertility area, the higher the organic compost doses, the higher the values of most vegetatitve characteristics of radish plants and the chemical properties of the soil in both dates. for root fresh weight, the values ranged from 4.63 to 9.15 g in the control without organic compost and in the highest dose, respectively. in “high” soil fertility area, only k content in soil has not remained high for all organic compost doses, and the values ranged from 2.8 and 4.5 mmolc dm-3, in control without organic compost and in the highest dose, respectively. the residual effect of organic compost was confirmed by the increasing on the radish production in initial “high”soil fertility area.

Production and nutrients accumulation of endive under different doses of organic compost

This research aimed to evaluate the effects of doses of organic compost on the production and macronutrients accumulation of endive plant in two areas with different fertility levels. The experiments were conducted at the Experimental Farm Sao Manuel, located in the municipality of Sao Manuel-SP. The study was done in a complete random experimental design with seven treatments and four replications. The treatments consisted of different doses of organic compost (0, 35, 70, 105, 140 and 175 t ha -1 ) and a treatment with inorganic fertilizer. Vegetative characteristics (shoot fresh and dry matter weight, number of leaves, plant height and nutrients accumulation in the aerial part of the plant) were evaluated at the end of the cycle. It can be concluded that the higher the organic compost dose (in the studied range), the higher the production (shoot fresh weight) and nutrients accumulation of endive in either high and low fertility area. In the aerial part, the decreasing order of nutrients accumulation was: potassium > nitrogen > calcium > phosphorus > sulphur > magnesium, with the highest values of 1269, 471, 185, 91, 53 and 35 mg plant -1 , respectively.

Case of carbonized rice in the composition of substrates for emergency and production of changes Acacia mangium Willd

The objective of this study was to evaluate the influence of carbonized rice husk on initial growth of Acacia mangium Willd seedlings. The experiment was carried out in the forest of the Federal University of Tocantins, Campus of Gurupi-TO, conducted in a completely randomized design, with five treatments T1: 0% Carbonized Rice Peel (CAC) + 100% Bioflora® Commercial Substrate, T2 : 25% CCS + 75% Commercial substrate; T3: 50% CAC + 50% Commercial substrate; T4: 75% CAC + 25% Commercial substrate; T5: 100% CAC + 0% Commercial substrate, with 4 replicates, each replicate with 18 seeds. The percentage of emergence (% E), shoot height (H), shoot diameter (DC), shoot dry matter weight (PMSPA), root dry weight (PMSR) and dry matter weight Total (PMST). The results indicated that the use of carbonized rice husk added in different proportions to commercial Bioflora ® substrate presented significant results in the parameters analyzed in Acacia mangium Willd seedlings. It is suggested that 25% CAC + 75% of Bioflora® commercial substrate is used in the alternative substrate formulation, considering that this treatment was the one that presented the best result in initial growth of Acacia mangium Willd seedlings.

English

Successful stand establishment is prerequisite for optimum crop yields and can be affected by seeding depth. A field experiment was conducted to investigate the effects of seeding depth on agronomical characteristics, structural feature of subcrown internode (SCI), plant growth and ultimately grain yield of winter wheat. Seeds of Luyuan 502 were sown at four seeding depths (10, 25, 40 and 55 mm). The results showed that increasing the seeding depth from 10 to 40 mm increased seedling emergence rate, numbers of fall tillers per unit area and per plant. Seeding at 55-mm depth significantly decreased the seedling emergence, tillering capacity, spikes per unit m 2 ; however, the fertile tiller percentage significantly increased compared with shallower seeding. At 10-mm soil depth, there was no SCI produced; at 25 to 55-mm soil depth, the length of SCI increased with increasing of depth. However, the diameter of SCI and diameter and wall thickness of SCI xylem vessel decreased. Regarding hormonal concentration in SCI, GA3 and IAA increased with increasing seeding depth, whereas the maximum ZR and ABA contents were observed at 40-mm soil depth. Similarly, the maximum rate of oxygen consumption was also observed in SCI of 40-mm-sown plants. Transmission electron microscope observations showed many mitochondria in the companion cell (CC) and many plasmodesma connecting CC and sieve element. As the seeding depth increased, values of the normalized difference vegetative index and shoot dry matter weight decreased but interestingly, the highest grain yield was obtained in 40-mm-sown wheat, followed immediately by that at 55-mm depth. It is concluded that wheat sown at about 40-mm soil depth may be optimal for winter wheat growth and production in northern China.

Common bean yield under water suppression and application of osmoprotectants

ABSTRACT The objective of this study was to evaluate the performance of the common bean crop grown with application of osmoprotectants based on algae of the genus Durvillaea potatorum in the winter crop season, with occurrence or not of water suppression. The experiment used a randomized block design, in split plots, arranged in a 4x7 factorial scheme, in which the plots were composed of four treatments - periods of water suppression (7, 14, 21 days and the control treatment: 100% of field capacity throughout the crop cycle) and the subplots consisted of seven types of osmoprotectants. The treatments with osmoprotectants was applied during the full flowering of the common bean. Three days after application of osmoprotectants, the treatments with suppression of irrigation were established. The use of osmoprotectants based on algae of the genus Durvillaea does not affect the variables plant height, stem diameter, stem and pod dry matter, first pod height, number of pods per plant and number of grains per pod in common bean plants cultivated with occurrence of water suppression. Common bean plants under water restriction conditions have lower leaf and shoot dry matter and lower 100-grain weight. Common bean grain yield was influenced by the type of osmoprotectants and the water suppression period.

Germinação in vitro e aclimatização de Hamatocactus setispinus

Seed propagation preserves the population genetic variability and helps selecting desirable features. This study evaluated the in vitro germination of Hamatocactus setispinus in six different culture media, 1- MS basal medium full strength; 2- half-strength MS basal medium; 3- 1.0 g L-1 of Peter’s CalMag® 15-05-15 formulation; 4- 0.5 g L-1 of Peter’s CalMag® 15-05-15 formulation; 5- MS basal medium supplemented with 10% coconut water and; 6- water and agar, with and without activated charcoal, and the speed of germination index, the mean germination time and the germination rate, root length, shoot length and the number of roots were evaluate. The seedlings with superior development obtained from in vitro germination were acclimatized in two substrates: Biomix® Floreira; Biomix® Floreira + sand. Seedling survival, shoot length, shoot diameter, root length, root number, shoot fresh matter weight, root fresh matter weight, shoot dry matter weight and root dry matter weight were evaluated. Peter’s 1.0 g L-1 medium without activated charcoal led to the best results for root length (11.36 mm) and root number (3.84). There was 100% of seedling survival. Acclimatization substrates did not differ among themselves and, therefore, they did not affect seedling growth.

Soybean productivity under different grazing heights ofBrachiaria ruziziensisin an integrated crop-livestock system

The aim was to evaluate the effects of grazing height of Brachiaria ruziziensis on the production of straw, and the establishment and grain yield of a soybean crop, under an integrated crop-livestock system, on a typic dystrophic Red Latosol at the Experimental Farm of the Agronomic Institute of Paraná (IAPAR), in Xambrê, in the state of Paraná, Brazil (PR). The study was carried out between September of 2010 and April of 2012. The experimental design was of randomised blocks, in lots split over time, with five treatments and three replications. The following were determined for the Brachiaria ruziziensis: shoot dry matter weight, plant residue dry matter weight, and total dry matter weight (Brachiaria ruziziensis shoot weight + plant residue weight). Also determined were variables related to the yield of the soybean crop (number of plants per metre, plant height and grain productivity), for the crop years 2010/2011 and 2011/2012. Straw production is greater in areas of Brachiaria ruziziensis where there is no grazing compared to areas where grazing occurs; the high production seen in areas with greater grazing heights should also be noted. The final number of plants, plant height and productivity in the soybean were not affected by the grazing height of the Brachiaria ruziziensis.

Iron efficiency of different corn hybrids grown in nutrient solution culture

Growing Fe-efficient genotype(s) could be considered as a preferred genetic approach to tackle the widespread constraint of Fe-deficiency-/lime-induced chlorosis in crop grown on alkaline soil. This study aimed to investigate morphological and physiological traits linked to expression of Fe deficiency among four corn (Zea mays) including sweet (Z. mays sacchrata cvs. H403 and H404) and grain (Z. mays indentata cvs. H500 and H700) hybrids grown in nutrient solution using two Fe concentrations (5 and 50 µM Fe-ethylenediaminetetraacetic acid (Fe-EDTA)). Significant variation was found among studied hybrids in their tolerance to Fe-deficiency stress. Sweet corn hybrids were more sensitive to Fe deficiency as compared with grain corn hybrids and greater reduction was observed in their shoot dry matter at the 5 µM Fe-EDTA treatment. The greatest decrease in plant height, leaf area, and root and shoot dry matter weight under Fe-deficiency condition was found for H403 hybrid. No significant correlation was found between shoot and root Fe concentration with crop tolerance to Fe deficiency. Furthermore, different response of corn hybrids to Fe deficiency is an important factor, which has to be considered in Fe fertilizer recommendation as well as breeding programs.

Phytotechnical aspects of rooted stem cuttings of coffee.

The cloning of F1 Coffea arabica hybrids may represent a significant decrease in time and resources spent on coffee plant improvement programs. With the objective to obtain a methodology that allows an efficient cloning of C. arabica L. plants through stem cutting, two experiments were carried out in a green house with automatic mist system. In the experiment Rubi cultivars cuttings were used. The efficiency of root bed heating, exogenous sucrose supply (30 g.L-1), and six concentrations of IBA on the rooting of cuttings and formation of seedlings was tested. The evaluations were carried out 45, 90 and 180 days after installation. The results showed that sucrose did not have a positive effect on any of the analyzed variables. The root bed heating was effective for the ‘Rubi’. Bed heating associated with IBA did not increase the total percentage of ‘Rubi’ rooted cuttings. Nevertheless it increased the number of roots, root and shoot dry matter weight.

Associações genotípicas entre componentes de produção e caracteres agronômicos em feijão-caupi

A análise de coeficiente de correlação é uma importante ferramenta no estudo da associação entre os caracteres de feijão-caupi e para avaliar a contribuição de cada fator na produtividade desta cultura. Objetivou-se investigar as relações genotípicas entre a produtividade de grãos em feijão-caupi e alguns componentes de produção e características agronômicas, utilizando a análise de trilha para decompor as correlações em seus efeitos diretos e indiretos. O experimento foi realizado no período de maio a agosto de 2010. Foram utilizadas as cultivares BR8 Caldeirão, IPEAN V69, BRS Guariba e BR17 Gurguéia. Estimou-se as correlações genotípicas entre pares de caracteres e seus efeitos diretos e indiretos considerando os componentes de produção (número de vagens.planta-1 e número de sementes.vagem-1), caracteres agronômicos (altura da planta, área foliar e peso da matéria seca da parte aérea) e a produtividade de grãos. O diagrama de trilha com duas cadeias mostrou-se adequado em explicar as relações entre componentes primários, secundários e produtividade, considerando as altas estimativas dos coeficientes de determinação (R²) e baixos efeitos residuais. O número de vagens.planta-1 e a área foliar foram os caracteres mais correlacionados com a produtividade e se mostram eficientes em praticar-se seleção indireta, com o intuito de obter ganhos genéticos sobre o rendimento de grãos. Também mostraram ser caracteres importantes sobre os efeitos indiretos do número de sementes vagem-1, altura da planta e peso da matéria seca da parte aérea.

Improving effects of mycorrhizal symbiosis on sorghum bicolor under four levels of drought stress

This study was conducted to determination the symbiotic effects of arbuscular mycorrhizal (AM) fungi on the shoot and root characteristics and mycorrhiza influence on relationships between minerals (phosphorus and Nitrogen) acquisition and yield components under drought stress in Sorghum bicolor. A pot experiment was carried out in Shiraz, Iran in 2010 growing season. The experiment was conducted using split-plot arrangements in a randomized complete block design (RCBD) with three replications. Treatments were based on drought stress in four levels and mycorrhiza infection stages consisted of mycorrhiza inoculated (M1) and non-mycorrhiza (M0). The results showed that the drought stress had significant influences on root colonization percent, shoot dry matter weight, plant height, leaf area, root dry matter weight, root/shoot ratio, root length and root wet weight. It seems to be that the mycorrhiza had visibly increased the biomass of sorghum by impacts on the root characteristics, such as: root weight, root length, and root/shoot ratio. The cluster analysis indicated that shoot dry matter weight was correlated with root dry matter weight in non-mycorrhizal condition. Plant height and root length traits were also correlated with leaf area and root wet weight. While, these relations changed in mycorrhizal condition and plant height, leaf area, root wet weight and root length were correlated with root colonization percent. Also cluster analysis indicated the great improvement in relations between morphological traits and nutrients absorption and yield components by effects of mycorrhizal inoculation.

Compatibilidade do tratamento de sementes de feijão-caupi com fungicidas e inoculação com estirpes de Bradyrhizobium

O objetivo deste trabalho foi avaliar a compatibilidade do tratamento de sementes com fungicidas e a inoculação com estirpes de Bradyrhizobium em feijão-caupi. Em laboratório, avaliou-se a sobrevivência de células nas sementes da cultivar BRS Guariba, tratadas ou não com fungicidas (fludioxonil, carbendazim, carbendazim + thiram e carboxin + thiram) e inoculadas ou não com Bradyrhizobium (estirpes UFLA3-84, BR 3267, INPA3-11B e BR 3262). Em casa de vegetação, conduziu-se experimento em vasos de Leonard, com os mesmos tratamentos. Foram avaliados: massa de matéria seca da parte aérea, além de número e massa de nódulos 25 dias após a emergência das plantas. No campo, dois experimentos foram conduzidos, tendo-se utilizado a estirpe BR 3262, com aplicação de fungicidas nas sementes: um em área de primeiro cultivo e outro em área cultivada anteriormente com culturas anuais. Avaliaram-se, aos 35 dias, o número de nódulos, a massa de nódulos secos e a massa de matéria seca da parte aérea, e, na colheita, a produtividade de grãos. Os fungicidas não tiveram efeito significativo sobre a sobrevivência de Bradyrhizobium, a nodulação das plantas e o rendimento de grãos, que, em média, foi superior a 1.200 kg ha-1. O tratamento de sementes de feijão-caupi com fungicidas é compatível com a inoculação das estirpes avaliadas.

Development of a Method for Testing Dehydration Tolerance in Rice (Oryza sativa L) and its Application to a Recombinant Inbred Line Population

A recombinant inbred line population derived from Japonica rice cultivar Hyogokithanishiki and Indica rice cultivar Hokuriku-142 is a valuable source for genetic and molecular studies as these two parents have different origins. Characterization of the two parents under different biotic and abiotic stress conditions exploits novel research areas such as QTL analysis. In the present study two parents were evaluated for dehydration tolerance using Petri dish method and nursery box method. Average root length, shoot length, root dry matter and shoot dry matter weight were evaluated in each method. Shoot length in nursery box method gave a significant difference between two cultivars with Hygokithanishiki dehydration tolerant and Hokuriku-142 dehydration susceptible. The method was applied to evaluate 163 recombinant inbred lines (RILs) derived from the two parents for dehydration tolerance. The trait showed a normal distribution in the population with some transgressive lines expressing greater dehydration tolerance than dehydration tolerant parent Hyogokithanishiki. Therefore nursery box method is proposed as a reliable method for the evaluation of dehydration tolerance of rice cultivars and this method is suitable for evaluating germplasm collections and breeding populations for dehydration tolerance in rice breeding. DOI: http://dx.doi.org/10.4038/tare.v14i3.4846 Tropical Agricultural Research & Extension 14(3): 2011 76-82